JP5625140B2 - ORGANIC LIGHT-EMITTING MATERIAL, ORGANIC LIGHT-EMITTING MATERIAL MANUFACTURING METHOD, AND ORGANIC LIGHT-EMITTING ELEMENT - Google Patents

Description

  The present invention relates to an organic light emitting material, a method for producing the organic light emitting material, and an organic light emitting element. In particular, when a film is formed, an organic light-emitting material excellent in horizontal orientation and the like (hereinafter sometimes referred to as an oriented light-emitting material), a method for producing such an organic light-emitting material, and such an organic light-emitting material The present invention relates to an organic light emitting device using as a host material.

Conventionally, as an attempt to improve the light emission efficiency of an organic electroluminescence device (organic EL device), it has been proposed to use phosphorescence instead of fluorescence.
That is, in the light emitting layer of the organic EL element, a high amount of phosphorescent light emitting material is included with respect to the main component host material, and high emission efficiency is achieved by mainly using the excited triplet state of the phosphorescent light emitting material. Expected to be. This is because when an electron and a hole are recombined in an organic EL element, an excited singlet state and an excited triplet state having different spin multiplicity are generated at a ratio of 1: 3. Because.
Therefore, when using fluorescence that is light emission when returning from the excited singlet state to the ground state, only about 25% of the exciton (100%) can be used, whereas the excited triplet state is changed to the ground state. When using phosphorescence, which is light emission when returning, many excitons can be used. That is, by causing intersystem crossing, it can be changed to an exciton that emits phosphorescence, so that the excited singlet state changes to an excited triplet state, and 100% of the exciton can be used. Improvement in luminous efficiency is expected.

Thus, in order to improve the light emission efficiency in this way, an organic EL element having a light emitting layer formed by doping a carbazole compound as a host material and doping a phosphorescent iridium complex material has been proposed (for example, patents). Reference 1).
More specifically, it is an organic EL device in which an anode, a light emitting layer containing a phosphorescent iridium complex material, an electron transport layer made of an organic compound, and a cathode are sequentially stacked, An organic EL device comprising an iridium complex material in a range of 0.5 to 8% by weight using a carbazole compound as a host material.
As a typical phosphorescent iridium complex material, tris (2-phenylpyridine) iridium (hereinafter sometimes referred to as Ir (PPY) ₃ ) represented by the following formula (A) is disclosed. Yes.

In addition, a phosphorescent organometallic complex having a predetermined structure and a light-emitting element containing the same in a light-emitting layer have been proposed in order to improve the light-emitting characteristics and the lifetime of the element (for example, see Patent Document 2).
More specifically, β-dicarbonyl at the end of the long carbon chain represented by the following formula (B) and two 2-phenylpyridine molecules are coordinated to a platinum atom or the like, and the carbon chain There has been proposed a light-emitting element (organic EL element) in which β-dicarbonyl at the other end is a phosphorescent organometallic complex having a similar coordination structure and is contained in a light-emitting layer.

On the other hand, a high-efficiency, long-life organic light-emitting device using a predetermined fluorine-containing triphenylamine compound as a dopant material and a predetermined host material has been proposed (for example, see Patent Document 3). .
More specifically, a fluorine-containing triphenylamine compound represented by the following formula (C) is used as a dopant material in the light emitting layer, and a fluorene compound represented by the following formula (D) or (E) is used as a host material. It is an organic light emitting element characterized by using.

JP 2001-313178 A (Claims etc.) JP 2007-277170 A (Claims etc.) Japanese Patent No. 4311707 (claims, etc.)

However, both the phosphorescent iridium complex material disclosed in Patent Document 1 and the phosphorescent organometallic complex disclosed in Patent Document 2 have insufficient horizontal orientation when formed into films, respectively. Since the transition moments are not uniform, there has been a problem that a phosphorescent light emitting device having high luminance cannot be obtained yet.
In addition, when the phosphorescent iridium complex material disclosed in Patent Document 1 and the phosphorescent organometallic complex disclosed in Patent Document 2 are used in the light emitting layer of the organic EL element, respectively, as host materials There was also a problem that the range of addition amount that can be blended was narrow with respect to the carbazol compound.

Furthermore, since the fluorine-containing triphenylamine compound disclosed in Patent Document 3 is used as a dopant material and cannot emit phosphorescence, there has been a problem that the luminous efficiency is still low.
In addition, the organic light-emitting material disclosed in Patent Document 3 must use a predetermined fluorene compound as a host material, which increases the cost of the resulting organic light-emitting material and is disadvantageous economically. It was seen.
In addition, when the methyl group is introduced into the para position of the terminal phenyl group as in the organic light-emitting material disclosed in Patent Document 3, the amorphous property of the thin film made of organic molecules tends to be remarkably lowered. Although it is suitable for use as a host material, it has been conventionally considered disadvantageous for use as a host material.

Therefore, in view of the circumstances as described above, the present inventors show good horizontal orientation and the like when a film is formed by introducing a predetermined donor-acceptor structure in the molecule. When used as a host material of a luminescent material, it was found that a relatively high current value can be obtained even when a low voltage is applied, and a high external luminous efficiency (EQE) can be obtained, and the present invention has been completed. Is.
That is, an object of the present invention is to enable an organic light-emitting material exhibiting good horizontal orientation, an efficient manufacturing method of such an organic light-emitting material, and a low-voltage drive using such an organic light-emitting material. An organic light emitting device is provided.

  According to the present invention, represented by the following general formula (1), an electron acceptor tetrafluoroarylene structure is formed at the central portion, and a diphenylamine structure is formed at both ends via an electron donor arylene group. An organic light emitting material characterized by having a donor-acceptor type molecular structure comprising, and being used as a host material can solve the above-mentioned problems.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. )

That is, by having a donor-acceptor type molecular structure in the molecule, excellent horizontal orientation and the like can be obtained when the film is formed.
Therefore, when such an organic light emitting material is used as a host material in a light emitting layer of an organic EL element (phosphorescent light emitting element), a relatively high current value can be obtained even when a low voltage is applied. High external quantum efficiency (EQE) can be obtained even by low current injection.
In addition, the diphenylamine structures present at both ends are considered to improve the amorphous properties, respectively, and such an organic light-emitting material can effectively suppress crystallization of the host material as a whole, Even if the blending amount is relatively wide, it is possible to obtain the effect of being able to uniformly mix and disperse.
The donor-acceptor type molecular structure is basically composed of an electron donor-type arylene group, an electron-acceptor-type tetrafluoroarylene structure, and an electron-donor-type arylene group sequentially arranged. It can be considered as one electron donor structure including a diphenylamine structure linked to the terminal of the donor arylene group.
That is, it can be considered that an arylene group including an electron donor diphenylamine structure, an electron acceptor tetrafluoroarylene structure, and an arylene group including an electron donor diphenylamine structure are sequentially arranged.

Further , by constituting the substituents R ^{1 to} R ⁴ and a to h in this way, it is possible to obtain an organic light emitting material that is relatively easy to manufacture, inexpensive and stable in characteristics.

Further, in constituting the organic light-emitting material of the present invention, it is preferable to set the order parameter calculated from the anisotropy of the extinction coefficient to a value within the range of -0.5 to -0.1.
By defining and configuring the order parameters in this way, it is possible to quantitatively manage the horizontality of the organic light-emitting material. As a result, when a predetermined organic light-emitting element is configured, low current injection is possible. However, it is possible to drive at a low voltage, and it is possible to extend the life and efficiency.

Further, in configuring the organic light emitting material of the present invention, in a three-dimensional space composed of XYZ axes, when the angle formed by the Z axis that is the vertical axis and the virtual axis direction of the molecules of the organic light emitting material is θ, The horizontal angle (θ2) represented by (90−θ) is preferably set to a value of 31 ° or less.
By defining the horizontal angle in this way, the horizontality of the organic light emitting material can be managed quantitatively. As a result, when a predetermined organic light emitting element is configured, a low voltage is applied. However, since a relatively high current value can be obtained, it is possible to extend the life and efficiency.

Moreover, another aspect of the present invention is represented by the following general formula (1), and an electron acceptor tetrafluoroarylene structure is formed in the central portion, and both ends thereof are bonded via an electron donor arylene group. This is a method for producing an organic light-emitting material having a donor-acceptor type molecular structure each containing a diphenylamine structure and used as a host material.
Then, 1,4-a first step of preparing a dihalogenated aryl halides consisting tetrafluoroethylene arylene, first boronic acid ester consisting of para-amino arylboronic acid ester having a substituent R ¹ to R ^2, and substituents A palladium catalyst comprising a second step of preparing a second boronic acid ester comprising a paraaminoaryl boronic acid ester having R ^{3 to} R ⁴ , a halogen at one terminal of the aryl halide, and the first boronic acid ester And the base nucleophilic species are cross-coupled, and then the halogen at the other end of the aryl halide and the second boronic acid ester are cross-linked by the action of the palladium catalyst and the base nucleophilic species. And a third step of coupling the organic light-emitting material.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. )

By carrying out like this, when forming into a film, the predetermined organic luminescent material excellent in horizontal orientation etc. can be manufactured efficiently.
Therefore, by using such an organic light-emitting material as a host material for the light-emitting layer in an organic EL element, a relatively high current value can be obtained even when a low voltage is applied. High external quantum efficiency (EQE) can also be obtained by implantation.
When the types of the substituents R ^{1 to} R ^{2 and} the types of the substituents R ^{3 to} R ⁴ are different, that is, an organic light-emitting material having an asymmetric structure, or the types of the substituents R ^{1 to} R ² and When the types of the substituents R ^{3 to} R ⁴ are the same, that is, even if the organic light emitting material has a symmetric structure, it can be efficiently produced, for example, in two steps.

In carrying out the method for producing an organic light-emitting material of the present invention, in the third step, the first boronic ester and the second boronic ester are added dropwise to the aryl halide while cross-cups are added. It is preferable to ring.
When implemented in this way, even when the activity of the boronic acid ester is short, fresh boronic acid ester is always supplied by dripping. Therefore, the boronic acid ester is effectively used for cross-coupling. A predetermined organic light-emitting material can be efficiently manufactured, both symmetrically and asymmetrically.
That is, by carrying out in this way, a predetermined boronic acid ester can be effectively reacted even with an aryl halide considered to have a strong electron acceptor property and a very low reactivity such as Suzuki coupling. The yield of the predetermined organic light emitting material can be dramatically improved.

Still another embodiment of the present invention is represented by the following general formula (1 ′), wherein an electron acceptor tetrafluoroarylene structure is formed at the central portion, and an electron donor arylene group is interposed at both ends thereof. Thus, there is provided a method for producing an organic light emitting material having a donor-acceptor type molecular structure each containing a diphenylamine structure and used as a host material.
Then, a first step of preparing an aryl halide comprising 1,4-dihalogenated tetrafluoroarylene, and a boronic acid comprising a paraaminoaryl boronic ester having substituents R ^{1 to} R ² or substituents R ^{3 to} R ⁴ An organic light-emitting material comprising: a second step of preparing an ester; and a third step of cross-coupling the aryl halide and the boronic ester by the action of a palladium catalyst and a base nucleophile. It is a manufacturing method.

(In the general formula (1 ′), the substituents R ^{1 to} R ² (or R ^{3 to} R ⁴ ) and a to d (or e to h) are each independently a hydrogen atom or a carbon number of 1 -4 alkyl group, except that R ^{1 to} R ² (or R ^{3 to} R ⁴ ) are both methyl groups. )

By carrying out in this way, even when the activity life of the boronic acid ester is short, a fresh boronic acid ester is always supplied by dripping, so the boronic acid ester is effectively used for cross-coupling. Thus, a symmetrical organic light emitting material can be efficiently produced.
That is, a predetermined boronic acid ester can be effectively reacted even with an aryl halide considered to have a strong electron acceptor property and extremely low reactivity, and the yield of a predetermined organic light emitting material can be drastically increased. Can be improved.

  Further, another aspect of the present invention is represented by the following general formula (1): an electron acceptor tetrafluoroarylene structure at a central site, and an electron donor arylene group at both ends thereof. An organic light-emitting device comprising a light-emitting layer formed by blending a dopant material with an organic light-emitting material having a donor-acceptor type molecular structure each containing a diphenylamine structure.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. )

  With such a configuration, a relatively high current value can be obtained even when a low voltage is applied, and furthermore, an organic light emitting device that can obtain a high external quantum efficiency (EQE) even by low current injection. Can be obtained.

In constituting the organic light-emitting device of the present invention, the dopant material is preferably an iridium complex compound and a platinum complex compound, or one of them.
With this configuration, high-luminance light emission (phosphorescence) can be obtained more stably and over a long period of time by injection of a relatively low current.

  Further, in constituting the organic light emitting device of the present invention, the dopant material is represented by the following general formula (2), a linear conjugated structure, a 2-phenylpyridine ligand, a coordination metal, A horizontal alignment compound having an acetylacetonate ligand in the molecule is preferable.

(In General Formula (2), R ⁵ and R ⁶ are each independently, an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, carbon A substituted aryl group having 6 to 20 carbon atoms, a halogen atom, or an amino group, and a to l and o to s are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and 1 to 20 carbon atoms. A substituted alkyl group, a C 6-20 aryl group, a C 6-20 substituted aryl group, or a halogen atom, and the coordination metal M is platinum (Pt), iridium (Ir), nickel (Ni) , copper (Cu), or gold (Au), the repeating number m and n each are independently an integer of 0 to 4, and, m + n is Ri least 1 or more integer der, however, when m + n is 1, R ⁵ and R ⁶ are hydrogen atoms, Unless an unsubstituted alkyl group of prime 1-20.)

With this configuration, the horizontal orientation can be further improved by the action of the dopant material, and high-luminance light emission (phosphorescence) can be obtained stably and over a long period of time by injection of a relatively low current. be able to.
In addition, since a predetermined dopant material rich in horizontal orientation is used, when a film having a predetermined thickness is formed and irradiated with light from a predetermined angle (90 ° direction) to the film, the substrate is exposed. On the other hand, phosphorescence with high polarization can be obtained in the horizontal direction and can be added in a wide range of blending amounts with respect to the main component host material.

FIG. 1 is a JV plot of an organic EL device using a horizontally oriented organic light emitting material (Example 1). FIG. 2A is a diagram provided to explain the relationship between the external quantum efficiency of the organic EL element using the horizontally oriented organic light-emitting material (Example 1) and the current density. b) is a diagram provided to explain the relationship between the external quantum efficiency of an organic EL element using a non-horizontal alignment organic light-emitting material (Comparative Example 1) and the current density. FIGS. 3A to 3F are diagrams for explaining the effect of introducing a donor / acceptor structure in a horizontally oriented organic light-emitting material. FIGS. 4A to 4B are diagrams for explaining the alignment state in the non-horizontal alignment organic light emitting material (CBP). FIG. 5 is a sectional view of a basic organic EL element. FIG. 6 is a cross-sectional view of a modified example of an organic EL element including an electron injection layer. FIG. 7 is a diagram showing the relationship between the emission time t (μsec) in the phosphorescence emission spectrum of the organic EL element and the emission intensity. FIG. 8 is a diagram for explaining the relationship between the anisotropy of the extinction coefficient (k) and the wavelength (λ) of the organic light-emitting material with horizontal alignment (Example 1). FIG. 9 is an NMR chart of a horizontally oriented organic light emitting material (Example 1). FIG. 10 is an FT-IR chart of a horizontally oriented organic light emitting material (Example 1). FIG. 11 is an ultraviolet absorption spectrum of the horizontally oriented organic light emitting material (Example 1). FIG. 12 is an emission spectrum of a horizontally oriented organic light emitting material (Example 1). FIG. 13 is a molecular schematic diagram obtained by X-ray crystal structure analysis for explaining the molecular structure of a horizontal light-emitting organic light-emitting material (Example 1). FIG. 14A is an NMR chart of a horizontally oriented organic light emitting material ( Reference Example 2), and FIG. 14B is an FT-IR chart. FIG. 15A is a diagram for explaining the relationship between the anisotropy of the extinction coefficient (k) and the wavelength (λ) of the horizontally oriented organic light emitting material ( Reference Example 2). 15 (b) is an ultraviolet absorption spectrum, and FIG. 15 (c) is an emission spectrum. FIG. 16A is an NMR chart of a horizontally oriented organic light emitting material (Example 3), and FIG. 16B is an FT-IR chart. FIG. 17A is a diagram provided to explain the relationship between the anisotropy of the extinction coefficient (k) and the wavelength (λ) of the horizontally oriented organic light emitting material (Example 3). 17 (b) is an ultraviolet absorption spectrum, and FIG. 17 (c) is an emission spectrum. FIG. 18A is an NMR chart of a horizontally oriented organic light emitting material (Example 4), and FIG. 18B is an FT-IR chart. FIG. 19A is a diagram for explaining the relationship between the anisotropy of the extinction coefficient (k) and the wavelength (λ) of the horizontally oriented organic light emitting material (Example 4). 19 (b) is an ultraviolet absorption spectrum, and FIG. 19 (c) is an emission spectrum.

[First Embodiment]
A first embodiment of the present invention is represented by the following general formula (1), and an electron acceptor tetrafluoroarylene structure is formed at a central site, and both ends thereof are bonded via an electron donor arylene group. Each of the organic light-emitting materials has a donor-acceptor type molecular structure including a diphenylamine structure and is used as a host material.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. )

  Hereinafter, the aspect of the organic light emitting material according to the first embodiment of the present invention will be specifically described with reference to the drawings as appropriate.

1. Basic Structure The organic light-emitting material of the first embodiment is a compound represented by the above general formula (1), which includes an electron acceptor tetrafluoroarylene structure at the central site, and has electron donor properties at both ends. Each having a diphenylamine structure through the arylene group.
That is, by having a predetermined donor-acceptor type molecular structure in the molecule of the organic light-emitting material as the host material as the basic structure, the horizontal orientation of the molecule when the film is formed can be remarkably improved.

More specifically, the organic light-emitting material of the present invention (Example 1: DPAPFP) has excellent horizontal orientation during film formation, and as shown in the line A of the JV characteristic in FIG. A high current density is obtained even with the application of.
For example, when a voltage of 4.0 V is applied, a current density of 3.0 mA / cm ² is obtained. In the case of 4.5 V, 7.0 mA / cm ² and 5.0 V, A current density of 15.0 mA / cm ² is obtained.
On the other hand, the organic light-emitting material (Comparative Example 1: CBP) that is said to be at the highest light emission level at present is confirmed to be randomly oriented during film formation and is non-horizontally oriented.
For example, when a voltage of 4.0 V is applied, a current density of 0.8 mA / cm ² is obtained. In the case of 4.5 V, 3.0 mA / cm ² and in the case of 5.0 V, A current density of 8.0 mA / cm ² is obtained.
Therefore, as shown in the line B of the JV characteristic in FIG. 1, the JV characteristic is inferior to the present invention.
That is, it is understood that the organic light-emitting material excellent in horizontal alignment of the present invention has a current density that is twice or more that of the organic light-emitting material having non-horizontal alignment.
Further, the organic light-emitting material having excellent horizontal orientation according to the present invention is 10% or more even in a low current density region of about 1 × 10 ⁻³ [mA / cm ² ] as shown in FIG. High external quantum efficiency is stably obtained.
On the other hand, it is understood that the non-horizontal orientation CBP has a large current density dependency of the external quantum efficiency (EQE,%) as shown in FIG.
That is, it is understood that the organic light-emitting material having excellent horizontal alignment according to the present invention has a small current density dependency in a low current density region.

The reason for this will be described with reference to FIGS. 3A to 3F. The organic light-emitting material 10 of the present invention shown in FIG. 3A has a predetermined donor-acceptor type molecular structure 10 ′ in the molecule. This is because, by having (10a, 10b, 10a), a stacking phenomenon of a benzene-perfluorobenzene type occurs as shown in FIG.
More specifically, when assuming a plurality of molecules positioned in the vertical direction, as shown on the left side of the arrow in FIG. 3 (c), an arylene group (10a, 10a ′) having a donor property of a lower molecule, The electron acceptor tetrafluoroarylene structure (10b) of the upper molecule is close to each other, and as shown in FIG. 3 (d), it is relatively separated from one arylene structure in the horizontal direction and electrically in the vertical direction. It will be an inquiring relationship. Therefore, as shown on the right side of the arrow in FIG. 3C, the upper molecules are easily arranged in the horizontal direction due to the influence of the lower molecules already formed in the horizontal direction.
Furthermore, as shown on the left side of the arrow in FIG. 3 (e), when assuming a plurality of molecules positioned in the vertical direction and assuming that a plurality of upper molecules exist, donor properties can be obtained even between a plurality of upper molecules. It is presumed that the arylene group having the above and the electron acceptor tetrafluoroarylene structure of the upper molecule are close to each other and are layered.
Here, the stacking phenomenon of DPAPFP, which is a donor-acceptor type molecule represented by the formula (3) described later, will be described using a 3D molecular model obtained by X-ray crystal structure analysis as shown in FIG. .
As shown in FIG. 13, when a plurality of DPAPFP molecules exist, the molecules are horizontally aligned in the horizontal direction and are layered in the vertical direction. In particular, in the vertical direction, a tetrafluoroarylene group and a tetrahydroarylene group are present. It is understood that and are layered in close proximity.
Then, as shown on the right side of the arrow in FIG. 3 (e), such a layered molecule composed of a plurality of molecules is more easily arranged in the horizontal direction, and once aligned in the horizontal direction, It becomes difficult to reorient.
That is, the molecule 10 having the predetermined donor-acceptor type molecular structure 10 ′ is easily fixed in the horizontal direction. As shown in FIG. Since it becomes easy to arrange | position horizontally, it is concluded that the movement of an electric charge between molecules becomes smooth and a favorable JV characteristic is acquired.

In contrast, the non-horizontal alignment organic light emitting material (CBP) whose structural formula is shown in FIG. 4A has a biphenylene structure 30 'in the molecule, but a predetermined donor-acceptor type molecule. It is not a structure. Therefore, the above-described benzene-perfluorobenzene type interaction does not exist, and a plurality of molecules 30 are randomly oriented as shown in FIG. 4B.
That is, even if a plurality of molecules are arranged in the horizontal direction once due to the dopant material or the like, the vertical direction or the horizontal direction may not be fixed enough, so that it may move in the vertical direction. Sufficiently assumed.
In any case, in the case of a non-horizontal alignment organic light-emitting material, it is estimated that the movement of charge between molecules is hindered, and the JV characteristics are relatively inferior compared with a horizontal alignment organic light-emitting material. Is done.

Although not shown, the organic light emitting material as the host material not only defines itself, but also regulates the molecular arrangement of the dopant material contained in the light emitting layer to some extent, and improves the horizontal orientation of these materials together. It is estimated that
Therefore, when the organic light emitting material as the host material of the present invention is excited to emit light, the light emission traveling direction is aligned in a predetermined direction (the normal direction of the thin film), that is, the transition moment is aligned. Therefore, even higher light emission luminance can be stably obtained even at a low current value.

2. Type Specific examples of the compound represented by the general formula (1) include compounds represented by the following formulas (3) and (5) to (9) (provided that the formula (4) is a reference compound) )
That is, the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms .
This is because a compound represented by the following formula is relatively easy to produce, and an organic light-emitting material having low cost and stable characteristics can be obtained.

3. Horizontal orientation 1 (order parameter (S))
In addition, the organic light-emitting material represented by the general formula (1) is arranged in the horizontal direction with respect to the surface of the base material when the film is formed on the base material, that is, exhibits good horizontal orientation. I can say.
Here, it can be judged based on the order parameter (S) whether or not the organic light emitting material represented by the general formula (1) is arranged in the horizontal direction with respect to the substrate surface.
That is, the extinction coefficient (ko, ke) is actually measured with an ellipsometer, and then the order parameter can be calculated based on the formula (1) shown in Example 1 described later.
And if this order parameter is a value within the range of -0.5 to -0.1, it can be said that the organic light emitting materials are arranged substantially in the horizontal direction.
More specifically, when the order parameter exceeds -0.1, the horizontal orientation is insufficient, and the JV characteristics are not very good. On the other hand, when the order parameter is -0.5, It means that it is completely horizontally oriented.
Therefore, the order parameter is more preferably a value in the range of −0.5 to −0.2, and even more preferably a value in the range of −0.5 to −0.22.

4). Horizontal orientation 2 (Horizontal angle (θ2))
Furthermore, based on the horizontal angle (θ2) calculated from the order parameter (S), the horizontal orientation of the organic light emitting material as the host material can be determined.
That is, in accordance with the formula (1) shown in Example 1 described later, as shown in FIG. 3B, in the three-dimensional space composed of the XYZ axes, the Z axis that is the vertical axis and the molecules of the organic light emitting material The angle (θ) formed by the virtual axis direction can be calculated.
When an organic thin film made of an organic light emitting material is formed on the substrate, as shown in FIG. 3B, the horizontal angle (θ2), which is an angle formed by the virtual axis direction of the molecules of the organic light emitting material, is ( 90−θ), the horizontal orientation of the organic light emitting material can be determined based on the horizontal angle.
More specifically, when the horizontal angle is 31 ° or less, the organic light emitting material as the host material is arranged substantially in the horizontal direction, the charge transfer becomes smooth, and the JV characteristic is It becomes good.
However, if the horizontal angle is excessively small, the types of usable organic light emitting materials may be excessively limited.
Therefore, the horizontal angle is preferably set to a value within the range of 1 to 27 °, and the horizontal angle is further preferably set to a value within the range of 1 to 26 °.

5. Luminescence quantum yield (Φ)
Moreover, it is preferable to make the light emission quantum yield ((PHI)) measured about the organic luminescent material as a host material into the value within the range of 30-80%.
This is because when the emission quantum yield becomes a value of less than 30%, the emission luminance of the phosphorescence obtained may be lowered, or it may be difficult to extract the polarization component.
On the other hand, when the light emission quantum yield exceeds 80%, the types of usable organic light emitting materials may be excessively limited.
Therefore, it is more preferable to set the emission quantum yield measured using the organic light emitting material as the host material to a value in the range of 40 to 75%, and further to a value in the range of 50 to 70%. preferable.
In addition, the light emission quantum yield measured using the organic luminescent material as a host material can be measured according to the method described in Example 1 mentioned later.

6). External quantum efficiency (EQE)
Further, an external quantum efficiency (EQE) measured when a predetermined organic EL element is configured using an organic light emitting material as a host material is a current density of 0.0005 to 10 mA / cm ² . In the range, a value of 10% or more is preferable.
This is because when the external quantum efficiency is less than 10%, the obtained light emission luminance may be excessively lowered.
On the other hand, when the external quantum efficiency is excessively high, for example, a value exceeding 20%, the types of usable dopant materials may be excessively limited.
Therefore, it is more preferable that the external quantum efficiency measured using the organic light emitting material as the host material is a value within a range of 10.5 to 18% within a predetermined current density range. More preferably, the value is within the range.
In addition, the external quantum efficiency measured using the organic luminescent material as a host material can be measured according to the method described in Example 1 described later.

7). Weight average molecular weight Moreover, it is preferable to make the weight average molecular weight of the organic luminescent material as a host material into the value within the range of 400-1000.
This is because when the weight average molecular weight is less than 400, the heat resistance and durability may be significantly reduced. On the other hand, when the weight average molecular weight exceeds 1000, it may be difficult to uniformly disperse the predetermined guest material.
Therefore, the weight average molecular weight of the organic light emitting material as the host material is more preferably set to a value within the range of 410 to 800, and further preferably set to a value within the range of 420 to 600.
In addition, this weight average molecular weight can be measured by the gel permeation chromatography (GPC) method by polystyrene particle conversion, for example.

[Second Embodiment]
The second embodiment of the present invention is represented by the general formula (1), and has an electron acceptor tetrafluoroarylene structure at the central portion and an electron donor arylene group at both ends thereof, respectively. A method for producing an organic light emitting material having a donor-acceptor type molecular structure comprising a diphenylamine structure and used as a host material.
Then, 1,4-a first step of preparing a dihalogenated aryl halides consisting tetrafluoroethylene arylene, first boronic acid ester consisting of para-amino arylboronic acid ester having a substituent R ¹ to R ^2, and substituents A palladium catalyst comprising a second step of preparing a second boronic acid ester comprising a paraaminoaryl boronic acid ester having R ^{3 to} R ⁴ , a halogen at one terminal of the aryl halide, and the first boronic acid ester And the base nucleophilic species are cross-coupled, and then the halogen at the other end of the aryl halide and the second boronic acid ester are cross-linked by the action of the palladium catalyst and the base nucleophilic species. And a third step of coupling the organic light-emitting material.
Hereinafter, the manufacturing method of the predetermined | prescribed organic luminescent material which is the 2nd Embodiment of this invention is demonstrated concretely, referring drawings suitably.

1. Scheme In the scheme, the aryl halide prepared in the first step and the second step and the boronic ester are cross-coupled by the action of a palladium catalyst and a base nucleophile, respectively, and the above-described general formula (1) is used. It is the manufacturing method of the organic luminescent material represented.
That is, by using the Suzuki-Miyaura coupling method (SMC method) for cross-coupling an organoboron compound and an aryl halide to obtain an asymmetric biaryl by the action of a palladium catalyst and a base nucleophile, the above-described method is used. The organic light emitting material represented by the general formula (1) has an advantage that it can be produced efficiently in a short time.

2. First Step The first step is a step of preparing a tetrafluoroaryl halide comprising 1,4-dihalogenated 2,3,5,6-tetrafluoroarylene prior to cross coupling.
That is, as the predetermined tetrafluoroaryl halide, 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 1,4-dichloro-2,3,5,6-tetrafluorobenzene, 1,4 -Preparation of at least one of diiodo-2,3,5,6-tetrafluorobenzene and the like.
Such an aryl halide can be produced according to a known synthesis method, or a commercially available product can be used as it is.

3. Second Step The second step is a step of preparing a predetermined boronic ester prior to cross coupling.
In other words, the substituents R ¹ to R ² first boronic acid ester consisting of para-amino arylboronic acid ester having a (substituent R ¹ to R ² are the same contents as the general formula (1).), And substituted In the step of preparing a second boronic acid ester composed of a paraaminoaryl boronic acid ester having groups R ^{3 to} R ⁴ (substituents R ^{3 to} R ⁴ have the same contents as in general formula (1)), respectively. is there.
Therefore, in order to obtain an organic light-emitting material having an asymmetric structure, the substituents R ^{3 to} R ⁴ must be different from the substituents R ^{1 to} R ^2. The substituents R ^{3 to} R ⁴ in a given boronic acid ester must be the same as the substituents R ^{1 to} R ² (the same applies to the substituents a to d and the substituents ef). ). That is, in order to obtain an organic light-emitting material having a symmetric structure, either the first boronate ester or the second boronate ester is prepared and cross-coupled with the aryl halide as described later. .
More specifically, as the predetermined boronic acid ester, 1,4- {4- (diphenylamino) phenyl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 1,4- {4- (bis (4-methylphenyl) amino) phenyl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 1,4- {4- (4-methyl) (phenyl) Amino) phenyl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 1,4- {4- (diphenylamino) -2-methylphenyl} -4,4,5,5- Tetramethyl-1,3,2-dioxaborolane, 1,4- {4- (diphenylamino) -3-methylphenyl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 2- {4- (Di-tert-butylphenylamino) fur It is preferable to prepare at least one of enyl-1-yl} 4,4,5,5-tetramethyl-1,3,2-dioxaborolane and the like.
Such a boronic ester can be produced according to a known synthesis method, or a commercially available product can be used as it is.

4). Third Step As shown in the reaction formula (1) and the reaction formula (2), the third step is an aryl halide represented by the formula (8) prepared in the first step and the second step, respectively (the symbol X is Br, Cl or I) and the prescribed boronic acid ester represented by formula (9) and formula (10) are sequentially cross-coupled by the action of a palladium catalyst and a base nucleophile, respectively, This is a step of forming an organic light emitting material represented by (1).

Here, in the third step, the predetermined boronic acid ester represented by the formula (9) and the formula (10) is dropped to the aryl halide represented by the formula (8), and the cross coupling is sequentially performed. It is preferable to make it.
The reason for this is that the activity of a given boronic acid ester tends to decrease in the reaction vessel. This is because the yield can be improved.
More specifically, a predetermined boronic acid ester can be effectively reacted with an aryl halide, which has a strong electron acceptor property and is generally considered to have a very low reactivity, and a predetermined organic light emission. The yield of the material can be dramatically improved. For example, when batch treatment is performed without dropping, the yield of about 1% can be improved to a yield of 50% or more when boronic ester is dropped and reacted. confirmed.
An example of suitable conditions when a predetermined boronic acid ester is dropped and reacted with a predetermined aryl halide is shown below.
Reaction temperature: 20-80 ° C
Dropping time: 5 to 36 hours Dropping speed: 0.05 to 0.4 molar equivalent / hour

In addition, when the organic light emitting material represented by the general formula (1) has an asymmetric structure with respect to the diarylamine consisting of the substituents R ^{1 to} R ² and the diarylamine consisting of the substituents R ^{3 to} R ⁴ , the reaction formula As shown in (1) and reaction formula (2), one boronic ester represented by formula (9) or formula (10) is first subjected to a cross-coupling reaction, and then the other boronic ester is cross-coupled. A ring reaction is performed, and a cross-coupling reaction is basically performed in two steps.
On the other hand, when the organic light-emitting material represented by the general formula (1) has a symmetric structure with respect to the diarylamine composed of the substituents R ^{1 to} R ² and the diarylamine composed of the substituents R ^{3 to} R ⁴ , As in the modified example, the cross-coupling reaction may be basically generated in one step using any one of the predetermined boronic acid esters represented by the formula (9) and the formula (10).

5. Modified Example A modified example of the production method is represented by the general formula (1 ′), and an electron acceptor tetrafluoroarylene structure is formed at the central portion, and an electron donor arylene group is interposed at both ends thereof. The organic light-emitting material has a donor-acceptor type molecular structure each containing a diphenylamine structure and has a symmetrical structure used as a host material.
Then, a first step of preparing an aryl halide comprising 1,4-dihalogenated tetrafluoroarylene, and a boronic acid comprising a paraaminoaryl boronic ester having substituents R ^{1 to} R ² or substituents R ^{3 to} R ⁴ A method for producing an organic light-emitting material, comprising: a second step of preparing an ester; and a third step of cross-coupling an aryl halide and a boronic ester by the action of a palladium catalyst and a base nucleophile. .
That is, by implementing in this way, a symmetrical organic luminescent material can be manufactured efficiently.
Further, by dropping a predetermined boronic acid ester to the aryl halide, a fresh boronic ester is always supplied even when the boronic acid ester has a short active period. The reactivity with respect to can be improved.
Therefore, according to the dropping method, a highly active boronic acid ester can be used to efficiently produce cross coupling, and a symmetrical organic light-emitting material can be produced in a very short time.

[Third Embodiment]
The third embodiment of the present invention is represented by the general formula (1), and an electron acceptor tetrafluoroarylene structure is formed at the central portion, and an electron donor arylene group is provided at both ends thereof. An organic light-emitting device comprising a light-emitting layer formed by blending a dopant material with an organic light-emitting material having a donor-acceptor type molecular structure containing a diphenylamine structure as a host material.
A light emitting device comprising a light emitting layer or a plurality of organic thin film layers including a light emitting layer between a pair of electrodes consisting of an anode and a cathode, wherein the light emitting layer is a dopant material and a host material as a main component As an organic light-emitting device comprising the organic light-emitting material of the first embodiment.
Hereinafter, the organic light emitting device (organic EL device) according to the third embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

1. Basic Configuration An organic light emitting device of the present invention, for example, a typical organic EL device 110, as shown in FIG. 5, is made of an anode 102 made of a transparent conductive material and a predetermined organic compound on a transparent substrate 101 such as glass. A hole transport layer 103 made of, a light emitting layer 104 made of a predetermined organic compound, a hole blocking layer 105 made of a predetermined organic compound, an electron transport layer 106 made of a predetermined organic compound, and a cathode 107 made of a metal material are laminated. ing.
That is, the organic EL element 110 is configured using such a multilayer structure as a basic configuration, and high-luminance phosphorescence can be emitted by recombination with electrons and holes respectively injected from the electrodes.

  Another structure of the organic EL element 111 includes a structure in which an electron injection layer 107a is laminated as a thin film between the electron transport layer 106 and the cathode 107 as shown in FIG.

2. Light-Emitting Layer The light-emitting layer contains a dopant material with respect to the host material together with the organic light-emitting material (host material) of the first embodiment.
Here, the type of the dopant material is not particularly limited, but high-intensity phosphorescence can be obtained more stably and over a long period of time by relatively low current injection. Therefore, the iridium complex compound and platinum It is preferable to use a complex compound or one of them.
Whether or not phosphorescence is emitted can be determined by, for example, the emission lifetime of the phosphorescent material using Quantaurus-Tau (manufactured by Hamamatsu Photonics), which is a small fluorescence lifetime measuring device. .
That is, as shown in FIG. 7, when the emission spectrum of phosphorescence is measured and the predetermined emission intensity (Log ₁₀ (number of photons)) persists in the order of μsec or more, it is determined that the obtained emission is phosphorescence. can do.

Here, specific examples of the dopant material such as an iridium complex compound will be shown while comparing with the emission color.
That is, as an iridium complex compound for extracting blue phosphorescence, bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) tetrakis (1-pyrazolyl) borate, bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate, bis {2- [3 ′, 5′-bis (trifluoromethyl) phenyl] pyridinato-N, C ^{2 ′} } iridium (III) picolinate, bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) acetylacetonate, and the like.

As iridium complex compounds for extracting green phosphorescence, tris (2-phenylpyridinato-N, C ^{2 ′} ) iridium (III), bis (2-phenylpyridinato-N, C ^{2 ′} ) Iridium (III) acetylacetonate, bis (1,2-diphenyl-1H-benzimidazolato) iridium (III) acetylacetonate, bis (benzo [h] quinolinato) iridium (III) acetylacetonate, tris (benzo [ h] quinolinato) iridium (III) and the like.

Further, as an iridium complex compound for taking out yellow phosphorescence, bis (2-phenylpyridinato-N, C ^{2 ′} ) (2- (3- (2-oxo-2H-chromenyl)) pyridinato-N, C ^{4 ′} ) iridium (III), bis (2,4-diphenyl-1,3-oxazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate, bis [2- (4′-perfluorophenylphenyl) Pyridinato] iridium (III) acetylacetonate, bis (2-phenylbenzothiazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate, (acetylacetonato) bis [2,3-bis (4-fluoro Phenyl) -5-methylpyrazinato] iridium (III), (acetylacetonato) bis {2- (4-methoxyphenyl) -3,5-dimethylpyrazinato} i Examples include lithium (III).

As iridium complex compounds for extracting orange phosphorescence, tris (2-phenylquinolinato-N, C ^{2 ′} ) iridium (III), bis (2-phenylquinolinato-N, C ^{2 ′} ) iridium ( III) Acetylacetonate, (acetylacetonato) bis (3,5-dimethyl-2-phenylpyrazinato) iridium (III), (acetylacetonato) bis (5-isopropyl-3-methyl-2-phenylpyra) Zinato) iridium (III) and the like.

Furthermore, as an iridium complex compound for extracting red phosphorescence, bis [2- (2′-benzo [4,5-α] thienyl) pyridinato-N, C ^{3 ′} ] iridium (III) acetylacetonate, Bis (1-phenylisoquinolinato-N, C ^{2 ′} ) iridium (III) acetylacetonate, (acetylacetonato) bis [2,3-bis (4-fluorophenyl) quinoxalinato] iridium (III), (acetyl Acetonato) bis (2,3,5-triphenylpyrazinato) iridium (III), (dipivaloylmethanato) bis (2,3,5-triphenylpyrazinato) iridium (III) and the like It is done.

Examples of the platinum complex compound include bis (2-phenylpyridinato-N, C ^{2 ′} ) platinum (II), (2-phenylpyridinato-N, C ^{2 ′} ) platinum (II) acetylacetonate, (N, N′-bis (salicylidene) ethylenediaminato-N, N ′, O, O ′) platinum (II), (tetraphenylporfinato-N, N ′, N ″, N ″ ″) platinum One type alone or a combination of two or more types such as (II) is preferable.

Furthermore, regarding the kind of dopant material, it is preferable to use the horizontal orientation material represented by General formula (2). In addition, iridium and platinum are also used for the horizontal alignment material represented by the general formula (2). However, unlike the above-described iridium complex compounds and platinum complex compounds, they should be complex compounds other than those. Is the premise.
In particular, a phosphorescent material represented by the following formulas (11) to (19) is more preferable because the quantum efficiency is large and phosphorescence with high luminance can be stably obtained.

Moreover, it is preferable to make the compounding quantity of dopant material into the value within the range of 0.1-20 weight% with respect to the quantity (100 weight%) of the whole luminescent material which consists of dopant material and host material.
The reason for this is that when the blending amount of the dopant material is less than 0.1% by weight, the emission luminance may be remarkably lowered.
On the other hand, when the compounding amount of the dopant material exceeds 20% by weight, it may be difficult to uniformly disperse or easily crystallize with respect to a predetermined host material. .
Therefore, the blending amount of the dopant material is more preferably set to a value within the range of 1 to 10% by weight, and further to a value within the range of 2 to 8% by weight with respect to the total amount of the light emitting material. preferable.

Moreover, it is preferable to make the weight average molecular weight of dopant material into the value within the range of 400-1000.
This is because when the weight average molecular weight is less than 400, the heat resistance and durability may be significantly reduced. On the other hand, when the weight average molecular weight exceeds 1000, it may be difficult to uniformly disperse the predetermined host material.
Therefore, the weight average molecular weight of the dopant material is more preferably set to a value within the range of 410 to 800, and further preferably set to a value within the range of 420 to 600.
In addition, this weight average molecular weight can be measured by the gel permeation chromatography (GPC) method by polystyrene particle conversion, for example.

  In addition, it is also preferable to add a material that assists electron transport to the light emitting layer. Examples of such electron transport auxiliary materials include triazole derivatives, oxazole derivatives, polycyclic compounds, heteropolycyclic compounds such as bathocuproine, oxadiazole derivatives, fluorenone derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, anthraquinones. Dimethane derivatives, anthrone derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, acid anhydrides of aromatic ring tetracarboxylic acids such as naphthalenetetracarboxylic acid or perylenetetracarboxylic acid, phthalocyanine derivatives, 8-quinolinol derivatives One or two or more of metal complexes, metal phthalocyanines, various metal complexes represented by metal complexes having benzoxazole or benzothiazole as a ligand, organosilane derivatives, iridium complexes, etc. Like a combination of.

3. Anode As the anode, a metal material or a metal oxide material having a relatively large work function, more specifically, 4 eV or more is used.
As such a metal material, for example, at least one of indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like is preferable.
The thickness of the anode is usually preferably set to a value in the range of 300 to 3000 angstroms.

4). Cathode For the cathode, a material having a relatively small work function, more specifically, a metal material or metal oxide material of less than 4 eV is used.
As such a metal material, for example, lithium, barium, aluminum, magnesium, indium, silver, or an alloy thereof is preferable.
And it is preferable to make the thickness of a cathode into the value within the range of 100-5000 Angstrom normally.
In addition, if either one of the anode or the cathode described above is transparent or translucent such as indium tin oxide (ITO), predetermined phosphorescence can be extracted to the outside.

5. Electron Transport Layer As shown in FIGS. 5 to 6, the electron transport layer includes at least the light emitting layer 104, the anode 102, the cathode 107, and a hole blocking layer 105 described later, and an electron transport layer at a predetermined position. 106 is preferably provided.
Here, examples of the electron transport material to be blended in the electron transport layer include, for example, triazole derivatives, oxazole derivatives, polycyclic compounds, heteropolycyclic compounds such as bathocuproine, oxadiazole derivatives, fluorenone derivatives, diphenylquinone derivatives, thiols. Pyrandioxide derivatives, anthraquinone dimethane derivatives, anthrone derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, acid anhydrides of carbocyclic aromatic tetracarboxylic acids such as naphthalenetetracarboxylic acid or perylenetetracarboxylic acid, phthalocyanine derivatives , 8-quinolinol derivative metal complexes, metal phthalocyanines, various metal complexes represented by metal complexes having benzoxazole or benzothiazole ligands, organic silane derivatives, iridium complexes, etc. Include combinations of the above German or two.

6). Hole blocking layer Moreover, it is preferable to provide the hole blocking layer 105 as shown in FIGS.
This is because by providing the hole blocking layer 105 in this manner, the light emission efficiency can be increased and the lifetime of the organic EL element can be increased.
Here, the hole blocking layer 105 can be provided by using the above-described electron transport material, and is preferably a mixed layer in which two or more kinds of electron transport materials are mixed and stacked by co-evaporation or the like. .
The electron transport material contained in the hole blocking layer preferably has an ionization potential greater than that of the light emitting layer.

7). Others Although not shown, the periphery of the display area of the organic EL element is sealed with a predetermined member while using an epoxy resin or an acrylic resin to eliminate the influence of moisture and enhance durability. Preferably there is.
An inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil is preferably injected into the gap between the display area of the organic EL element and the predetermined member.
On the other hand, in order to eliminate the influence of moisture, it is also preferable to make the gap a vacuum or to enclose a hygroscopic compound in the gap.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
1. Production of Organic Luminescent Material First, 1,4-bis {4- (diphenylamino) phenyl} -2 represented by the formula (3) from 1,4-dibromo-2,3,5,6-tetrafluorobenzene , 3,5,6-tetrafluorobenzene (hereinafter sometimes referred to as DPAPFP) was synthesized.
That is, after storing 1,4-dibromo-2,3,5,6-tetrafluorobenzene (commercial product, 608 mg, 2 mmol) as a raw material compound in a container equipped with a dropping device and a stirrer, the atmosphere was changed to a nitrogen atmosphere. , Tetrakis (triphenylphosphine) palladium (0) (200 mg, 0.17 mmol), potassium carbonate (2.54 mg, 18 mmol), 50 ml tetrahydrofuran (THF), and 12 ml water were added to degas. And then heated to 60 ° C.
Next, 1,4- {4- (diphenylamino) phenyl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (commercial product, 1485 mg, 4 mmol) was dissolved in 10 ml of THF. The degassed liquid was dropped over 12 hours, and further heated and stirred at 60 ° C. for 22 hours to obtain a reaction solution.
Then, the solvent is evaporated to dryness (evaporation) from the obtained reaction solution, and the resulting residual solid is collected by filtration. Further, the residual solid is dissolved in dichloromethane, and the solution is washed with water and saturated brine. After drying with magnesium sulfate, the solvent was evaporated to dryness and further residual solid was collected by filtration.
Finally, the obtained solid residue is purified by silica gel column chromatography and recrystallized using dichloromethane / hexane to give 1,4-bis { 4- (Diphenylamino) phenyl} -2,3,5,6-tetrafluorobenzene (DPAPFP, 675 mg, 1.06 mmol, 53% yield) was obtained.

2. Thin film formation using organic light-emitting material A thin film (thickness: 50 nm) made of the organic light-emitting material (DPAPFP) is formed on a silicon substrate (size: 10 mm × 10 mm × 0.7 mm) by vacuum evaporation. did.
In addition, as vapor deposition conditions, it is as follows.
Film forming device: E-180-S with ultra-precise alignment mechanism (manufactured by ALS Technology Co., Ltd.)
Film forming speed: 1.0 cm / sec.
Film forming pressure: 2.0 × 10 ⁻⁴ Pa
Film forming time: 9.3 minutes

3. Evaluation of organic light emitting material (1) Evaluation of order parameter (S) Substrate using an ellipsometer (M-2000 manufactured by JA Woollam Co., Ltd.) for a thin film of organic light emitting material (DPAPFP) obtained on a silicon substrate. The amplitude ratio and the phase difference (Psi and Delta) were measured as changes in the polarization state of the polarized light incident at different angles with respect to. Based on these values, an assumed optical model is constructed, fitting is performed so that the mean square error between the two is minimized, an extinction coefficient is calculated, and the following equation (1) is applied. Thus, the order parameter (S) was obtained. The obtained results are shown in Table 1.
The construction of the optical model, the fitting for minimizing the mean square error between the optical model and the actual measurement value, etc. were performed using WASE32 (manufactured by JA Woollam Co., Ltd.) which is software for ellipsometry data analysis.

Here, in Equation (1), symbol k is an extinction coefficient, and suffixes o and e are extinction coefficients in the xy direction (plane direction) and z direction (vertical direction) with respect to the substrate, respectively. It shows that. And the extinction coefficient (k) of the obtained organic luminescent material (DPAPFP) can be measured using the ellipsometer mentioned above. FIG. 8 shows the obtained extinction coefficient chart on the vertical axis and the wavelength on the horizontal axis.
In addition, in Formula (1), (theta) means the angle which the Z axis | shaft which is a perpendicular axis, and the virtual axis direction of the molecule | numerator of an organic light emitting material make in the three-dimensional space which consists of an XYZ axis.

(2) Horizontal orientation evaluation Further, from the value of the order parameter (S) described above, an angle (θ) formed by the Z axis that is the vertical axis and the virtual axis direction of the molecule of the organic light emitting material is calculated. As an index of horizontal orientation, an angle formed by the substrate and the virtual axis direction of the organic light emitting material (DPAPFP), that is, a horizontal angle (θ2 = 90−θ) was calculated. The obtained results are shown in Table 1.

(3) Luminescence quantum yield About the thin film of the obtained organic luminescent material (DPAPFP), using an absolute PL quantum yield measuring apparatus (Quantaurus-QY C11347-01, manufactured by Hamamatsu Photonics Co., Ltd.), a predetermined wavelength (337 nm). ) Quantum yield (internal quantum efficiency) was measured. The obtained results are shown in Table 1.

(4) NMR
NMR (nuclear magnetic resonance) of the obtained organic light emitting material (DPAPFP) was measured using JNM-EPC400 (manufactured by JEOL) in a state dissolved in a deuterated chloroform solvent. The obtained NMR chart is shown in FIG.

(5) FT-IR
The FT-IR chart of the obtained organic light emitting material (DPAPFP) was measured by KBr tablet method using FT / IR-6100 (manufactured by JASCO). The obtained FT-IR chart is shown in FIG.

(6) Light absorption wavelength spectrum and emission peak The light absorption wavelength spectrum of the obtained organic light emitting material (DPAPFP) was measured using UV-2550 (manufactured by Shimadzu Corporation) which is an ultraviolet-visible spectrophotometer.
Further, the emission intensity (fluorescence emission spectrum) in the obtained organic light emitting material (DPAPFP) was measured using a spectrofluorometer FP-6500 (manufactured by JASCO).
The obtained light absorption wavelength spectrum is shown in FIG. 11, and the obtained fluorescence emission spectrum is shown in FIG.

(7) J-V characteristics The following organic EL element was comprised using the obtained organic luminescent material (DPAPFP). Next, J-V characteristics (current density VS voltage) were measured. The obtained JV characteristic curve is shown in FIG. Table 1 shows current densities at typical voltages (4 V, 4.5 V, and 5 V).
(Configuration of organic EL element)
ITO (100 nm) / TPD (50 nm) / 6 wt% Ir (ppy) ₂ Pc-DPAPFP (20 nm) / TPBi (50 nm) / LiF (0.5 nm) / Al (100 nm)
That is, a glass substrate (12 mm long × 12 mm wide × 1 mm thick) on which an indium tin oxide film having a thickness of 100 nm was deposited was prepared as an anode.
On top of that, N, N′-bis (3-methylphenyl) -N, N′-bis (phenyl) -benzidine vapor deposition layer (TPD, 50 nm) as a hole transport layer and (Bis ( 2-phenylpyridinato-N, C2 ^′ ) (2- (3- (2-oxo-2H-chromenyl)) pyridinato-N, C4 ^′ ) iridium (III), hereinafter Ir (ppy) ₂ Pc DPAPFP vapor-deposited layer (20 nm) containing 6% by weight), and 2,2 ′, 2 ″-(1,3,5-benztolyl) -tris (as an electron transporting layer). 1-Phenyl-1-H-benzimidazole) vapor deposition layer (TPBi, 50 nm) and, as a cathode, a LiF vapor deposition layer (0.1 nm) and an Al vapor deposition layer (100 nm) are laminated and connected to a power source. Thus, an organic EL element was obtained.
In addition, as vapor deposition conditions, it is as follows.
Film forming device: E-180-S with ultra-precise alignment mechanism (manufactured by ALS Technology Co., Ltd.)
Film forming speed: Host 1.0 kg / sec. , Dopant 0.007 Å / sec.
Film forming pressure: 2.0 × 10 ⁻⁴ Pa
Film forming time: 3.7 minutes

(8) External quantum efficiency The organic EL element similar to the JV characteristic was measured, and the external quantum efficiency was measured. That is, the obtained external quantum efficiency is measured as a relationship with the current density, and the obtained characteristic curve is shown in FIG. Table 1 shows external quantum efficiencies at typical current densities (1 × 10 ⁻³ mA / cm ² , 1 × 10 ⁻¹ mA / cm ^2, and 1 × 10 ¹ mA / cm ² ).

[ Reference Example 2]
In Reference Example 2, 1,4-bis {4- (dimethylphenylamino) phenyl-1-yl} -2,3,5,6-tetrafluorobenzene represented by the formula (4) is synthesized as an organic light emitting material. Evaluation was performed in the same manner as in Example 1.
Therefore, FIG. 14 (a) shows the NMR chart, FIG. 14 (b) shows the FT-IR chart, and FIG. 15 (a) shows the anisotropic extinction coefficient (k) for the obtained organic light emitting material. FIG. 15B shows a light absorption wavelength spectrum, and FIG. 15C shows a fluorescence emission spectrum.

First, 1,4-bis {4- (dimethylphenylamino) phenyl-1-yl} -2 represented by the formula (4) from 1,4-dibromo-2,3,5,6-tetrafluorobenzene 3,5,6-tetrafluorobenzene was synthesized.
That is, after storing 1,4-dibromo-2,3,5,6-tetrafluorobenzene (commercial product, 616 mg, 2 mmol) as a raw material compound in a container equipped with a dropping device and a stirrer, the atmosphere was changed to a nitrogen atmosphere. , Tetrakis (triphenylphosphine) palladium (0) (200 mg, 0.17 mmol), potassium carbonate (2.54 mg, 18 mmol), 50 ml tetrahydrofuran (THF), and 12 ml water were added to degas. And then heated to 60 ° C.
Next, 2- {4- (dimethylphenylamino) phenyl-1-yl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.597 mg, 4 mmol) was dissolved in 10 ml of THF. The liquid material which was deaerated and dropped was dropped over 12 hours, and further heated and stirred at 60 ° C. for 72 hours to obtain a reaction solution.
Then, the solvent is evaporated to dryness (evaporation) from the obtained reaction solution, and the resulting residual solid is collected by filtration. Further, the residual solid is dissolved in dichloromethane, and the solution is washed with water and saturated brine. After drying with magnesium sulfate, the solvent was evaporated to dryness and further residual solid was collected by filtration.
Finally, the obtained solid residue is purified by silica gel column chromatography and recrystallized using dichloromethane / hexane to give 1,4-bis { 4- (Dimethylphenylamino) phenyl-1-yl} -2,3,5,6-tetrafluorobenzene (881 mg, 1.27 mmol, 63% yield) was obtained.

[Example 3]
In Example 3, 1,4-bis {4- (di-tert-butylphenylamino) phenyl-1-yl} -2,3,5,6-tetra represented by the formula (8) is used as the organic light-emitting material. Fluorobenzene was synthesized and evaluated in the same manner as in Example 1.
Therefore, FIG. 16A shows an NMR chart, FIG. 16B shows an FT-IR chart, and FIG. 17A shows an anisotropic extinction coefficient (k) for the obtained organic light-emitting material. FIG. 17 (b) shows a light absorption wavelength spectrum, and FIG. 17 (c) shows a fluorescence emission spectrum.

First, 1,4-bis {4- (di-tert-butylphenylamino) phenyl-1- represented by the formula (8) from 1,4-dibromo-2,3,5,6-tetrafluorobenzene Yl} -2,3,5,6-tetrafluorobenzene was synthesized.
That is, after storing 1,4-dibromo-2,3,5,6-tetrafluorobenzene (commercial product, 462 mg, 1.5 mmol) as a raw material compound in a container equipped with a dropping device and a stirring device, Add atmosphere, add tetrakis (triphenylphosphine) palladium (0) (150 mg, 0.13 mmol), potassium carbonate (1.91 mg, 13.5 mmol), 30 ml tetrahydrofuran (THF) and 9 ml water. After deaeration, the mixture was heated to 60 ° C.
Then, 15 ml of 2- {4- (di-tert-butylphenylamino) phenyl-1-yl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.450 mg, 3 mmol) A liquid obtained by dissolving in THF and degassing was dropped over 12 hours, and further heated and stirred at 60 ° C. for 48 hours to obtain a reaction solution.
Then, the solvent is evaporated to dryness (evaporation) from the obtained reaction solution, and the resulting residual solid is collected by filtration. Further, the residual solid is dissolved in dichloromethane, and the solution is washed with water and saturated brine. After drying with magnesium sulfate, the solvent was evaporated to dryness and further residual solid was collected by filtration.
Finally, the obtained solid residue is purified by silica gel column chromatography and recrystallized using dichloromethane / hexane to give 1,4-bis { 4- (Di-tert-butylphenylamino) phenyl-1-yl} -2,3,5,6-tetrafluorobenzene (1.013 mg, 1.18 mmol, 79% yield) was obtained.

[Example 4]
In Example 4, 1- {4- (diphenylamino) phenyl-1-yl} -4- {4- (dimethylphenylamino) phenyl-1-yl}-represented by the formula (9) as an organic light-emitting material 2,3,5,6-tetrafluorobenzene was synthesized and evaluated in the same manner as in Example 1.
Accordingly, FIG. 18A shows an NMR chart, FIG. 18B shows an FT-IR chart, and FIG. 19A shows an anisotropic extinction coefficient (k) for the obtained organic light emitting material. FIG. 19B shows a light absorption wavelength spectrum, and FIG. 19C shows a fluorescence emission spectrum.

First, 1- {4- (diphenylamino) phenyl-1-yl} -4- {4- represented by the formula (9) from 1,4-dibromo-2,3,5,6-tetrafluorobenzene. (Dimethylphenylamino) phenyl-1-yl} -2,3,5,6-tetrafluorobenzene was synthesized.
That is, 1- {4- (diphenylamino) phenyl-1-yl} -4-bromo-2,3,5,6-tetrafluorobenzene (473 mg) was used as a raw material compound in a container equipped with a dropping device and a stirring device. 1 mmol), nitrogen atmosphere, tetrakis (triphenylphosphine) palladium (0) (100 mg, 0.09 mmol), potassium carbonate (1.27 mg, 9.0 mmol) and 25 ml of tetrahydrofuran (THF). ) And 6 ml of water, and after deaeration, heated to 60 ° C.
Next, 2- {4- (dimethylphenylamino) phenyl-1-yl} -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (423 mg, 1 mmol) was dissolved in 5 ml of THF. The degassed liquid was added dropwise over 12 hours, and further heated and stirred at 60 ° C. for 15 hours to obtain a reaction solution.
Then, the solvent is evaporated to dryness (evaporation) from the obtained reaction solution, and the resulting residual solid is collected by filtration. Further, the residual solid is dissolved in dichloromethane, and the solution is washed with water and saturated brine. After drying with magnesium sulfate, the solvent was evaporated to dryness and further residual solid was collected by filtration.
Finally, the obtained residual solid is purified by silica gel column chromatography and recrystallized using dichloromethane / hexane to give 1- {4- (1) represented by the formula (9) as a white powder. Diphenylamino) phenyl-1-yl} -4- {4- (dimethylphenylamino) phenyl-1-yl} -2,3,5,6-tetrafluorobenzene (221 mg, 0.33 mmol, 33% yield) Got.

[Comparative Example 1]
In Comparative Example 1, 4,4′-di (N-carbazolyl) biphenyl (sometimes referred to as CBP) represented by the formula (20) is used as the host material, and the order parameter ( S) or the like was evaluated, or an organic EL element was configured to evaluate JV characteristics, external quantum efficiency, and the like.
FIG. 1 shows the obtained JV characteristic curve as line B, and FIG. 2B shows the obtained external quantum efficiency as a relationship with the current density.
The current density at typical voltages (4 V, 4.5 V, and 5 V), and the typical current densities (1 × 10 ⁻³ mA / cm ² , 1 × 10 ⁻¹ mA / cm ² and 1 × 10). Table 1 shows the external quantum efficiencies at ¹ mA / cm ² ).

In Examples 1, 3, 4 and Reference Example 2 , all of the order parameters are −0.34 or less and the horizontal angle is 19 ° or less, and an organic light-emitting material having excellent horizontal orientation is obtained. Obtained.
In Example 4 using an organic light emitting material having an asymmetric molecular structure, a high emission quantum yield of 80% or more was obtained.
On the other hand, the compound of Comparative Example 1 had an order parameter of 0.1, was randomly oriented when a plurality of molecules existed, and was non-horizontal.

As described above in detail, according to the present invention, when a film is formed, an organic light-emitting material as a host material exhibiting excellent horizontal orientation and the like, an efficient method for producing such an organic light-emitting material, and Even when a low voltage is applied, a relatively high current value can be obtained, and furthermore, an organic EL element (phosphorescent light emitting element) exhibiting a high external quantum efficiency (EQE) can be obtained by injection of a low current. It became so.
Further, according to the method for producing an organic light-emitting material of the present invention, in particular, in the third step, a predetermined boronic ester is dropped with respect to the aryl halide while being cross-coupled. The acid ester can be used as fresh, and the reaction yield can be dramatically improved even for aryl halides which are usually said to have low reactivity.

10: Host material (molecule of host material)
10 ': Donor-acceptor type molecular structure 12: Substrate (glass substrate)
20: Dopant material 30: Non-horizontal orientation host material (molecule of host material)
110, 111: Organic EL element 101: Transparent substrate 102: Anode 103: Hole transport layer 104: Light emitting layer 105: Hole blocking layer 106: Electron transport layer 107: Cathode 107a: Electron injection layer

Claims (10)

A donor represented by the following general formula (1), comprising an electron-accepting tetrafluoroarylene structure at a central site and a diphenylamine structure at each end via an electron-donating arylene group An organic light emitting material having an acceptor type molecular structure and used as a host material.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. ) The organic light-emitting material according to claim 1, wherein the order parameter calculated from the anisotropy of the extinction coefficient is set to a value in the range of -0.5 to -0.1. In a three-dimensional space composed of XYZ axes, a horizontal angle (θ2) represented by (90−θ), where θ is an angle formed by the Z axis that is the vertical axis and the virtual axis direction of the molecule of the organic light emitting material. the organic light-emitting material according to claim 1 or 2, characterized in that the the 31 ° following values. A donor represented by the following general formula (1), comprising an electron-accepting tetrafluoroarylene structure at a central site and a diphenylamine structure at each end via an electron-donating arylene group A method for producing an organic light emitting material having an acceptor type molecular structure and used as a host material,
A first step of preparing an aryl halide comprising a 1,4-dihalogenated tetrafluoroarylene;
A ^first boronic acid ester comprising a paraaminoaryl boronic acid ester having substituents R ^{1 to} R ² and a ^second boronic acid ester comprising a paraaminoaryl boronic acid ester having substituents R ^{3 to} R ⁴ are prepared. A second step;
After the halogen at one end of the aryl halide and the first boronic ester are cross-coupled by the action of a palladium catalyst and a base nucleophile, the other end of the aryl halide is A third step of cross-coupling the halogen and the second boronic acid ester by the action of a palladium catalyst and a base nucleophile;
A method for producing an organic light-emitting material comprising:

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. ) In the third step, with respect to the aryl halide, the first boronic acid ester and the second boronic acid esters, with each dropwise addition, according to claim 4, characterized in that the cross-coupling The manufacturing method of organic luminescent material. It is represented by the following general formula (1 ′), and comprises an electron acceptor tetrafluoroarylene structure at the central portion and a diphenylamine structure at both ends via an electron donor arylene group, respectively. A method for producing an organic light-emitting material having a donor-acceptor type molecular structure and used as a host material,
A first step of preparing an aryl halide comprising a 1,4-dihalogenated tetrafluoroarylene;
A second step of preparing a boronic acid ester comprising a paraaminoaryl boronic acid ester having substituents R ^{1 to} R ² or substituents R ^{3 to} R ⁴ ;
A third step in which the aryl halide and the boronic ester are cross-coupled by the action of a palladium catalyst and a base nucleophile;
A method for producing an organic light-emitting material comprising:

(In the general formula (1 ′), the substituents R ^{1 to} R ² (or R ^{3 to} R ⁴ ) and a to d (or e to h) are each independently a hydrogen atom or a carbon number of 1 -4 alkyl group, except that R ^{1 to} R ² (or R ^{3 to} R ⁴ ) are both methyl groups. ) The method for producing an organic light-emitting material according to claim 6 , wherein in the third step, the boronic acid ester is cross-coupled to the aryl halide while dropping. A donor represented by the following general formula (1), comprising an electron-accepting tetrafluoroarylene structure at a central site and a diphenylamine structure at each end via an electron-donating arylene group An organic light-emitting device comprising a light-emitting layer in which an organic light-emitting material having an acceptor-type molecular structure is used as a host material and a dopant material is blended therewith.

(In the general formula (1), the substituents R ^{1 to} R ⁴ and a to h are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms , provided that R ^{1 to} R ⁴ are Except when both are methyl groups. ) The organic light emitting device according to claim 8 , wherein the dopant material is an iridium complex compound or a platinum complex compound, or one of them. The dopant material comprises a linear conjugated structure represented by the following general formula (2), a 2-phenylpyridine ligand, a coordination metal, and an acetylacetonate ligand in the molecule. The organic light-emitting device according to claim 8 , wherein the organic light-emitting device is a horizontal alignment compound.

(In General Formula (2), R ⁵ and R ⁶ are each independently, an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, carbon A substituted aryl group having 6 to 20 carbon atoms, a halogen atom, or an amino group, and a to l and o to s are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and 1 to 20 carbon atoms. A substituted alkyl group, a C 6-20 aryl group, a C 6-20 substituted aryl group, or a halogen atom, and the coordination metal M is platinum (Pt), iridium (Ir), nickel (Ni) , copper (Cu), or gold (Au), the repeating number m and n each are independently an integer of 0 to 4, and, m + n is Ri least 1 or more integer der, however, when m + n is 1, R ⁵ and R ⁶ are hydrogen atoms, Unless an unsubstituted alkyl group of prime 1-20.)

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